1. Field of the Invention
The present invention relates to a color printer which prints a color image in accordance with color image data of each of separated colors.
2. Description of the Related Art
There is a need for realizing a full color recorder, such as a full color laser printer, for taking the place of conventional monochrome printers. In response, a color printer has been proposed, which includes a laser scanning unit, a photosensitive drum which receives a laser emitted from the laser scanning unit, and developing units having toner of different colors including yellow, cyan (blue), magenta, and black, etc.
In this color printer, the emission of the laser is controlled in accordance with color image data of separated colors. The laser is first emitted from a first laser scanning unit onto a photosensitive drum in accordance with color image data of a first color to form an electrostatic latent image for the first color. After the latent image is developed by the first developing unit, a charged or electrified recording paper is brought into contact with the photosensitive drum, so that a toner image for the first color is transferred to the recording paper. Thereafter, the above-mentioned operation including the formation of the electrostatic latent images for the remaining colors onto the same photosensitive drum, the development, and the transfer onto the same recording paper are repeated. Thereafter, when the toner images transferred onto the recording paper are fixed by a heat roller, etc., a fixed color image can be formed.
However, in a conventional color printer, a long time is required for printing, due to a presence of a plurality of developing units whose number corresponds to the number of colors (color image data) for one photosensitive drum. Moreover, the selective connection of the developing units
driving system thereof causes an undesirable oscillation or irregular rotation of the photosensitive drum, etc., thus resulting in a deterioration of the image quality.
There is also known a color printer which includes the same number of photosensitive drums and developing units corresponding to the number of the colors (color image data), and laser scanning units whose number corresponds to the number of photosensitive drums. In this printer, since toner images of different colors are formed on the respective photosensitive drums, the printing time can be reduced. Nevertheless, the printer is large, complicated and expensive.